1. Field of the Invention
The invention relates to a digitizing screen apparatus which may employ a mechanism for displaying color graphic images by mixing colors within cells having at least one liquid crystal element and at least one filter element.
2. Description of Related Art
The patent literature discloses several attempts to produce a series of stored graphic images. One early technique was to drive a patterned backdrop with respect to a plurality of small apertures. Schemes such as the foregoing are described in U.S. Pat. Nos. 2,432,896; 2,507,975 and 3,742,631.
In U.S. Pat. No. 3,963,326, a data display panel is disclosed. Each cell of the display has a shutter type of mechanism which turns each cell on or off thus allowing each cell to either transmit light or to blank it out thereby producing an image. No provision is made for the mixing of colors within each cell nor to homogenize the color to produce a uniform color from each cell nor to effect an intermediate level of illumination. Each cell simply functions as an on or off mechanism.
Other U.S. Pat. Nos. of possible interest include U.S. Pat. Nos. 1,832,894; 3,335,457; 3,237,331; 3,314,179; 3,328,475; 3,568,346; 3,686,781; 3,783,539 and 3,987,558.
In addition to the foregoing, other efforts have been made to produce digital-like displays. For example, digitized screens can be found in places such as Times Square, New York City. According to one embodiment, a field of light bulbs is controlled by an array of photocells, each actuating a single bulb on the display screen through an amplifier circuit. Movies of shadow graphs and in some cases real shadows, are cast upon the screen from a control room behind the sign. The images projected on the photocells appear in lights on the display screen over the street.
Other, less costly efforts have been made to digitize images on a more modest scale. One device marketed under the name Channel 2000 incorporates a plurality of lenses. Another device known as Channel 1 used a single diffusing sheet and an egg crate separator.
It is also known in the prior art to produce a three dimensional image by projecting a moving picture on the front surface of a contoured screen.
A useful discussion of the design of light concentrators may be found in the book entitled THE OPTICS OF NONIMAGING CONCENTRATORS: Light and Solar Energy by W. T. Welford and R. Winston published in 1978 by Academic Press.
During the prosecution of my copending application, Ser. No. 917,151, the following patent references were also cited: 2,884,833; 2,663,960; and 4,333,707.